Method and article for electric arc welding one metallic workpiece to another



LAHHHHLB i UHUQD BU LRLHLJE P. c. VAN DER WILLIGEN ETAL 2,510,000 us'mon AND ARTICLE FOR ELECTRIC ARC WELDING ons METALLIC woaxpmcs TO mom Filed March 9 1948 May 30, 1 950 mvEN'roRs PAUL CHRISTIAAN VAN DER WILLIGEN SIMON DIRK BOON /o c 2% X Patented May 30, 1950 ANOTHER UNITED STATES PATENT OFFICE METHOD AND-ARTICLE FOR ELECTRIC ARC WELDING ONE METALLIC WORKPIECE T Application March 9, 1948. Serial No. 13,915 I In-the Netherlands March 14, 1947 4 Claims.

This invention relates to a method for electricarc welding in which use is not made of a bare welding wire or coated welding rod, but an arc is produced directly between the work-pieces to be secured together by employing'a semi-conductive, slag-forming solid member which is sufficiently conductive -for initiating the arc and establishes the-electrical contact between the work-pieces which are required to be secured together and are slightly spaced apart. In such a, method the welding are is of very short duration audit is provided that one work piece, usually a rod shaped member e. g. a bolt, is placed on the other at the desired moment, which is ensured by a suitable choice of shape and size of the semi-conductive slag-forming solid member, so that a more or less intricate control device is not necessary. A semi-conductive slag-forming solid member of such a suitable device of shape'and size'in' the form of a cap per se is described and claimed in applicants copending application Serial No. 13,914 filed March 9, 1948, for an Article for electric arcwelding one metallic work-piece to another.

The conductivity required for the semi-conductive slag-forming solid body in regard to initiation of the welding arc is obtainable by mixing a large quantity of metalpowder with constituents such as are used'in'slag-forming coating materials for welding rods.

According to the invention the semi-conductive slag-forming solid member is previously cemented to one of the work pieces to be welded together, by means of conductive cement which contains such a quantity of metal powder as is necessary for the said particular welding method.

As an example of such a gerp ent we may menh ,tion a mixture of '70 parts by weight of figpow- ?'"der and 30 parts by weight of water glass".

In practice the invention lends itself eminently for use with rod-shaped members, for instance bolts, of which the end that is to abut the other work-piece is furnished with the semi-conductive, slag-forming solid body in the form of a cap which is cemented to this end according to the invention. Thus it is possible for the industry to place on the market finished bolts obtained by mass-production for the said particular welding method.

To be complete it is pointed out that in the particular welding method to which the invention relates, a semi-conductive slag-forming solid body is preferred which does not give 01! any gases during the welding process so as to prevent the metal melted in situ during the short heating operation to 2 seconds; from being blown away from 2 the welding point with the consequent detrimental effect on the quality of the welded joint. As an example of such a semgg onductive slag-.forniing solid member we may mention diamante-.01 "lfii'aftsbyweight of calcium carbonate, 13 parts by weight of calcium mais rzfisaas lay-weight of begtgnite, 'Z'paits'by wEIght of ferro-mangapeas, 3 parts-by weight of ferrosilic'rfjl arcsb'y weight of ferro-ji taniunland' 53 parts by weight of irorr powder, which mixtureis heated-for one ho'urit 800 C. in a nwxidising atmosphere. On using a mixture e. g. of ra parts by weight saleiimgei Bearish? Weight of qalaiumflucaide, 12 parts by weight of lass powder; Zparts by weight of jerro-manga nes'e, parts by weight of ferroesilicon, 2 parts by"w'eight of igrrgtita niiii'ifafid 50 "parts by weight of iron. powder such "fpreheating. operation is not necessary.

In order that the invention may be clearly understood and readily carriedinto effect it will now be described more fully with reference to the accompanying drawing, given by way of example, which represents a metal red I comprising a hollow cap 2 which consists of a semi-conductive,

slag-forming mass which is cemented to the metal rod I by means of the layer of cement 3.

Such a cap is eminently suitable for using the aforesaid welding method, particularly when making use of .the invention. In Figs. 1 to 4 the process is illustrated diagrammatically for a better understanding of the invention. Fig. 1 represents the starting position in which the bar I to be welded is pressed onthe collar 4 in the cavity ofthe cap 2 resting on the metal work piece 5. Upon applying the voltage the semi-conductive material of the cap 2 passes current and an arc is struck between the metal rod I and the work piece 5. In the proximity of this arc melting occurs due to the high temperature so that we soon have the state shown in Figs. 2, 3 and 4 respectively. Fig. 4 illustrates the moment at which the metal bar under pressure, for instance spring pressure, is pressed on the work piece 5. In this event the quantity of molten metal is sufficient for establishing the welded Joint between the rod i and the work piece 5.

The welding process is promoted by the cemented hollow cap 2, since the risk of premature depression of the rod I prior to melting of the collar 4 (Fig. 2) is avoided.

What we claim is:

1. A method of electric-arc welding one metallic work-piece to another metallic work-piece which comprises the steps of cementing to an inwardly projectingpollar formed within an aperture extending completely through a semi-conductive slag-forming solid member, one of said work-pieces by means of conductive cement, placing said one of said work-pieces in operative relationship with said another work-piece so that said solid member abuts said another work-piece and acts as a spacer between both said workpieces, constantly biasing said one of said workpieces toward said another of said work-pieces, passing an electric current through said workpieces and said semi-conductive element so that an arc is struck between said work-pieces and said one work-piece is finally moved to abutting relationship with said another work-piece after the heat of the arc has melted at least said collar in said slag-forming member, and then interrupting the electric current passing through said work-pieces.

2. A welding work-piece comprising a metallic rod-shaped member and a semi-conductive, slagforming solid member having an inwardly pro- Jecting collar formed within an aperture extending completely through said solid member, said solid member being cemented to said metallic rod-shaped member at an end thereof by means oi conductive cement with said rod-shaped member protruding into the aperture in said solid member and engaging said inwardly projecting collar, said solid member extending beyond the end of said rod-shaped member in the direction of the longer dimension thereof.

3. A welding work-piece as claimed in claim 2 wherein said semi-conductive, slag-forming solid member consists of material which is non-gas evolving under the intense heat of a welding operation for which said work-piece is adapted.

4. A method of electric arc-welding one metallic work-piece to another metallic work-piece, comprising the steps oi placing a slag-forming semi-conductive solid body having a passageway 4 of varying diameter completely therethrough on said one work-piece with one end of the passageway opening on said one work-piece and said another work-piece inserted into the other end oi. said passageway a distance limited therein by the dimensions of said passageway to so be spaced from said one work-piece, passing a current through said work-pieces to initiate an are therebetween through said one end of the passageway, bringing the work-pieces into contact with one another after the current has passed through said work-pieces long enough to increase the diameter of said passageway in the region of the are by melting of the solid body in the said region to permit such contact, and then discontinuing the current.

PAUL CHRISTIAAN VAN nna WILLIGEN.

SIMON DIRK BOON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,108 Crecca June 9, 1942 2,043,960 Jones et al June 9, 1936 2,057,670 Crecca et a1 Oct. 20, 1936 2,326,865 Kennedy Aug. 17, 1943 2,370,100 White Feb. 20, 1945 2,384,403 Somers Sept. 4, 1945 2,429,175 Van der Willigen et al. Oct. 14, 1947 2,459,957 Palmer Jan. 25, 1949 2,474,531 Keir et al June 28, 1949 FOREIGN PATENTS Number Country Date 497,133 Great Britain Dec. 13, 1938 365,302 Italy Nov. 30, 1938 

